Study On Biological Characteristics Of Zophobas Morio And Its Function On Plastic Degradation

Zophobas morio belongs to Coleoptera, Tenebrionidae. Its larvae are rich in protein with high nutrient value and are mainly used as pet food. Biology and artificial rearing methods of Zophobas morio are studied in this research. Zophobas morio are found being able to feed plastic in the rearing. The preference of Zophobas morio larvae on different plastic products is observed, and the excretions of these insects fed with different plastic materials and products are collected separately and identified with TGA-SDTA and FTIR to reveal its function of degradation on plastics. Results are as follows:1. Zophobas morio is a kind of social insect, experiencing egg, larvae, pupae and adult stages in its life. It has one generation per year in lab in northern part of China. Both adults and larvae have negative phototaxis, hygrotaxis, cannibalism. The lavae bite their eggs and pupae, so they should be separated from their eggs and pupae. The adult stage lasts 100～160 days; Eggs hatch after oviposition about 7 days; the larva stage takes 150～200 days; pupal stage is about 10 days.2. Egg's developmental threshold temperature is 14.6℃and effective accumulated temperature 92.3(℃·d). Prepupa's developmental threshold is 10.7℃and effective accumulated temperature 102.4(℃·d). Pupa's developmental threshold temperature is 4.8℃and effective accumulated temperature 257.6(℃·d).3. Egg's development rate is positively correlated with temperature. The highest hatching rate is obtained at 27℃. Larvae are better under 30℃~33℃in the first month and 27℃is more favorable to the growth in the following months. Development rates of prepupal stage and pupal stage are positively correlated with temperature. The higher the temperature is, the lower the pupation rate is. Under high temperature, most larvae are used to pupate shrank and become black and then die. Pupae are more easily infected by bacteria and most infected emerged adults are non-reproductive and deformed.4. Formula 4 (weight of wheat bran: weight of cabbage = 1:3) is better for feeding larvae in the first month and formula 3 (weight of wheat bran: weight of cabbage = 1:2) can be used for feeding after the first month.5. Setting rearing density as 12~15 caput/cm2 in the first month, 3~9 caput/cm2 in the second month, 3~6 caput/cm2 in the third and fourth month, 3 caput/cm2 in the fifth month is favorable for the growth of larvae. Average weight of larvae increases with time in form of logistic curve and weight of larvae grows fastest in the third month.6. Zophobas morio larvae prefer the plastics that are relatively thin, soft and of higher degree of foam to thick, hard plastic products. The larvae fed with mixture of bran and plastics can grow normally.7. Excretion of Zophobas morio feeding on low density polyethylene (LDPE) has been found containing new components which may be intestinal secretion of larvae.8. Properties of ethylene-vinyl acetate copolymer (EVA) in excretion of Zophobas morio feed on EVA have been changed.9. The basic characteristics of linear low density polyethylene (LLDPE) and polyethylene foamed sheet (EPE) in excretion of Zophobas morio feed on LLDPE are not changed, but new components are found and properties have been changed greatly.10. Excretion of larvae feeding on Polyvinyl chloride (PVC) and expandable polystyrene (EPS) foam has significant changes in basic characteristics and components in excretion vary a lot too.